The study proposes to test a novel application of an efficacious behavioral treatment, voucher-based reinforcement therapy, to promote smoking abstinence. This is an exploratory/developmental grant application (R21), and can be characterized as Stage 1 research under the Behavioral Therapies Development Program. Under abstinence reinforcement therapy, patients receive desirable consequences (e.g., goods and services) contingent on providing objective evidence of abstinence. Although a large number of studies over the past 25 years indicate that abstinence reinforcement therapy is highly effective in promoting drug abstinence, few studies have applied the treatment to smoking. Objective evidence of smoking abstinence can be determined by breath carbon monoxide (CO) output, which is a simple, non-invasive, and immediate method of determining smoking status. To verify continued abstinence CO samples must be provided on a daily basis, which has presented an obstacle in applying the treatment to smokers. Therefore, the study will use a home-based monitoring system to verify smoking status, and reinforcement therapy to promote smoking abstinence. The home-based system will consist of a user-friendly computerized system to transmit real-time images of smokers providing CO samples. Thus, objective evidence of smoking status can be easily and frequently obtained. The results will help form the basis of a research program on developing home-based applications of abstinence reinforcement therapy for smokers. In particular, high-risk and "hard-core" smokers will be targeted, such as those who smoke even while suffering from cardiovascular disease and cancer. The project will also seek to develop cost-effective and practical applications of voucher reinforcement therapy for smokers. The proposed study will provide critical information about the potential utility of homebased behavioral interventions for initiating and maintaining smoking abstinence, and thus their ability to reduce the morbidity and mortality caused by smoking.